Chapter 15 Definitions Flashcards
Define Auditory-evoked potentials
Method of testing brainstem function by auditory stimulation combined with recording electrical potentials from the scalp.
Define Basilar section of the brainstem
Anterior part of the brainstem, containing predominantly motor system structures.
Define Cerebellar peduncles
Bundles of axons that connect the cerebellum with the brainstem. The superior peduncle connects with the midbrain, the middle peduncle with the pons, and the inferior peduncle with the medulla.
Define Cerebral peduncles
Most anterior part of the midbrain, formed by axons descending from the cerebrum to the pons, medulla, and spinal cord; specifically the corticospinal, corticobrainstem, and corticopontine tracts.
Define Cochlear nuclei
Site of synapse between first- and second-order neurons involved in hearing; located laterally at the pontomedullary junction.
Define Coma
Condition of being unarousable; no response to strong stimuli including strong pinching of the Achilles tendon.
Define Consciousness system
Neural connections governing alertness, sleep, and attention. Includes the reticular formation, ascending reticular-activating system, basal forebrain (anterior to the hypothalamus), thalamus, and cerebral cortex.
Define Corticobrainstem tracts
Axons that convey motor signals from the cerebral cortex to cranial nerve nuclei in the brainstem.
Define Delirium
Reduced attention, orientation, and perception associated with confused ideas and agitation.
Define Inferior olivary nucleus
Nucleus in the upper medulla that receives input from most motor areas of the brain and spinal cord; may alert the cerebellum to errors in movement. Axons from the inferior olivary nucleus project to the contralateral cerebellar hemisphere.
Define Locked-in syndrome
Almost complete inability to move (sometimes eye movements and eyelids can be voluntarily controlled), despite intact consciousness. Due to damage to descending activating pathways.
Define Locus coeruleus
Nucleus in the upper pons involved in the direction of attention, nonspecific activation of interneurons and lower motor neurons in the spinal cord, and inhibition of pain information in the dorsal horn. Transmitter produced is norepinephrine.
Define Medulla
Inferior part of the brainstem that contributes to the control of eye and head movements, coordinates swallowing, and helps regulate cardiovascular, respiratory, and visceral activity.
Define Obtunded
Sleeping more than is awake, and is drowsy and confused when awake.
Define Oculomotor complex
Includes the oculomotor nucleus and the oculomotor parasympathetic nucleus. The oculomotor nucleus supplies efferent somatic fibers to the extraocular muscles innervated by the oculomotor nerve. The oculomotor parasympathetic (Edinger-Westphal) nucleus supplies parasympathetic control of the pupillary sphincter and the ciliary muscle (adjusts thickness of the lens in the eye).
Define Olive
Small oval lump on the anterolateral medulla that lies external to the inferior olivary nucleus.
Define Pedunculopontine nucleus
Nucleus within the caudal midbrain that influences movement via connections with the globus pallidus, subthalamic nucleus, and reticular areas. The neurons produce acetylcholine.
Define Periaqueductal gray
Area around the cerebral aqueduct in the midbrain; involved in somatic and autonomic reactions to pain, threats, and emotions. Activity of the periaqueductal gray results in the fight-or-flight reaction and in vocalization during laughing and crying.
Define Pyramids
Ridges on the anteroinferior medulla that are formed by the lateral corticospinal tracts.
Define Raphe nuclei
Brainstem nuclei that modulate activity throughout the central nervous system; the major source of serotonin. The midbrain raphe nuclei are important in mood regulation and onset of sleep. Pontine raphe nuclei modulate activity in the brainstem and cerebellum. Medullary raphe nuclei modulate activity in the spinal cord via raphespinal tracts. Projections to the spinal cord inhibit transmission of nociceptive information, adjust levels of interneuron activity, and produce nonspecific activation of lower motor neurons.
Define Red nucleus
Sphere of gray matter that receives information from the cerebellum and cerebral cortex and projects to the cerebellum, spinal cord (via rubrospinal tract), and reticular formation. Activity in the rubrospinal tract contributes to distal upper limb extension.
Define Reticular formation
Complex neural network in the brainstem, including the reticular nuclei and their connections; the source of ascending and descending reticular tracts.
Define Stupor
Condition of being arousable only by strong stimuli, including strong pinching of the Achilles tendon.
Define Substantia nigra
One of the nuclei in the basal ganglia circuit, located in the midbrain. The compacta part provides dopamine to the caudate nucleus and putamen; the reticularis part serves as one of the output nuclei for the basal ganglia circuit.
Define Syncope
Loss of consciousness that is a result of an abrupt decrease in blood pressure that deprives the brain of adequate blood supply. Synonym: fainting
Define Tectum
Part of the midbrain posterior to the cerebral aqueduct, consisting of the pretectal area and the superior and inferior colliculi; involved in reflexive movements of the eyes and head.
Define Tegmentum
Posterior part of the brainstem, including sensory nuclei and tracts, reticular formation, cranial nerve nuclei, and the medial longitudinal fasciculus.
Define Vegetative state
Complete loss of consciousness without alteration of vital functions.
Define Ventral tegmental area
Region in the midbrain that provides dopamine to cerebral areas important in motivation and in decision making.
Define Vestibular nuclei
Site of synapse between first- and second-order neurons involved in detecting head movement and head position; located laterally at the pontomedullary junction
